Reverse transcriptase will be used to make a DNA copy of hemoglobin mRNA. This hemoglobin DNA will then be used as a template for synthesis of RNA or ribosubstituted DNA. In either case alpha-P32-nucleotides will be used as precursors. The highly labelled products will be investigated using standard RNA sequencing techniques or the DNA sequencing techniques developed in this laboratory. The latter are especially powerful for a variety of reasons. For example, they permit us to make specific cleavages at A or at C or at G residues, and we can use the sequence specific DNases such as T4 endonuclease IV to make specific preliminary cleavages. Ultimately we hope to apply these techniques to determine parts of the sequences of the much larger C-type viral genomes on the one hand and to compare the sequences of aberrant hemoglobin mRNAs with the normal mRNA sequences on the other.